1. Field of the Invention
The present invention generally relates to a pneumatic, hydraulic or hydropneumatic adjustment device with a tubular vessel under pressure. The tubular vessel is divided into two work chambers by a piston fastened to a piston rod, whereby there is a blocking device which can be activated by a tripping tappet or actuating device which runs longitudinally in the piston rod and is guided outward.
2. Background Information
Tripping devices of pneumatic, hydropneumatic or hydraulic adjustment and locking elements, or possibly detent elements, are used, for example, in locking gas pressure springs to adjust the height of the seats and backrests on chairs, or headrests and footrests on beds, or as hydraulic locking elements for the steering column adjustments of motor vehicles. The tripping devices used in those cases are mechanical tripping devices. The activation of the mechanical tripping devices takes place either directly on the tripping device, or by means of an activation element separate from the tripping device, in which the activation force is transmitted by a system of levers and/or by a Bowden cable.
Such tripping devices may be disclosed in German Laid Open Patent Appln. No. 3 934 960 and German Laid Open Patent Appln. No. 3 913 849. Hydraulic translations, as disclosed in German Laid Open Patent Appln. No. 3 934 960, or the addition of electrical energy, as disclosed in German Laid Open Patent Appln. No. 3 913 849, make it possible to reduce the activation forces and distances to a minimum.
On such mechanical tripping devices, one disadvantage is that the required activation force and/or the activation distance can be quite large, depending on the realization in question. An additional disadvantage is that with the mechanical tripping devices, there may not be an excessive distance between the activation mechanism and the tripping device, because an increasing distance results in a reduction of the efficiency of the mechanism.
That in turn necessitates an increase in the activation force. An additional disadvantage with continuous tripping (unlocking of the adjustment mechanism) on hydraulic and mechanical tripping systems is that a force must be applied permanently, and with electrical tripping systems, electrical energy must be added constantly.